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Analysis of point load test as a method for preliminary geotechnical classification of rocks

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Bulletin of the International Association of Engineering Geology - Bulletin de l'Association Internationale de Géologie de l'Ingénieur Aims and scope Submit manuscript

Abstract

This paper deals with the analysis of the point load compression test made on irregular-shaped rock fragments, proposed in the late 50’s by Protodiakonov.

An ample revision of the literature on the subject has been made, and a series of tests, using seven different types of rock materials, has been developed.

The results obtained from these tests showed that parameters generally used in literature to relate the unconfined compressive (or tensile) strength of materials, resulting from point load tests, can lead to scattered results, due mainly to the scale effect, of great evidence in such tests.

It seems possible to obtain compressive (and tensile) strength of rocks, if the ratio between failure load and the distance between load application poins, with a 3/2 exponent, is considered, in field work, as being the "point load strength index".

Resume

L’article présente une analyse critique de l’essai de compression sur échantillons irréguliers de roche, proposé par Protodiakonov vers la fin des années 50.

Tout d’abord on a fait une révision de la littérature disponible sur le sujet et, après, une série d’essais sur sept types différents de matériaux.

Les résultats obtenus ont montré que les paramètres plus utilisés, dans la littérature, pour définir la résistance à la compression (ou traction) des roches, d’après les essais ponctuels, peuvent provoquer une dispersion très importante des résultats.

Cependant, il nous semble valable de suggérer la possibilité de déterminer, sur le chantier, la résistance à la compression (ou traction) des roches, si l’on considère le quotient entre la charge de rupture et la distance entre les deux points d’application de cette charge, le dénominateur à la puissance 3/2, comme "l’indice de charge ponctuelle".

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References

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Authors and Affiliations

  1. the "Instituto de Pesquisas Tecnologicas de Sao Paulo", Brazil

    Guidicini G. (Geologist), Nieble C. M. (Mining Engineer) & A. T. de Cornides (Geologist)

Authors
  1. Guidicini G.
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  2. Nieble C. M.
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  3. A. T. de Cornides
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G., G., Nieble, C.M. & de Cornides, A.T. Analysis of point load test as a method for preliminary geotechnical classification of rocks. Bulletin of the International Association of Engineering Geology 7, 37–52 (1973). https://doi.org/10.1007/BF02635318

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